There is a major effort underway to help individuals and families who are struggling with the shooting, but there's also a lot of anger over missed clues and warning signs that might have helped authorities prevent it. "We see the tragic consequences of those failures", Sessions said in a statement.
Cruz, 19, has been charged on 17 counts of premeditated murder, one each for the students and staff who were shot to death Wednesday during a killing spree at the Marjory Stoneman Douglas High School in nearby Parkland, Florida.
The information should have been "assessed as a potential threat to life", the Federal Bureau of Investigation said, and forwarded to the agents in the Miami field office to investigate.
"We are still investigating the facts", FBI Director Christopher Wray said in a statement.
The FBI has also separately been criticized by some Republicans over its investigation of allegations of Russian meddling in the 2016 presidential election, heaping further scrutiny on the agency led by Wray since President Donald Trump fired James Comey previous year.
The comment, posted that month, said: "I'm going to be a professional school shooter".
"Because of these gun laws, people that I know, people that I love, have died, and I will never be able to see them again", said Delaney Tarr, a Marjory Stoneman Douglas student.
President Trump visited victims of the shooting Friday and vowed to tackle mental-illness issues, but many say that isn't enough.
"The FBI apologised? Tell that to families", he told Reuters news agency. He said no one would benefit from "a circus of a trial'". But the agency said Friday that agents failed to investigate.
The event calls for students and teachers to walk out of their schools at 10 a.m. local time for 17 minutes, to honor the 17 lives lost in Florida.
For Kurth, words don't cut it anymore: "As educators, we're taught that actions speak louder than words", she said.
Mother pleads for cannabis to treat epileptic boy
The Home Office denied the licence, saying the drug "cannot be practically prescribed, administered or supplied to the public". The decision comes despite support from some MPs, including those in the all-party parliamentary group on drug policy reform.